Dynamic routing system for short messages (SMS) sent by a calling party using a mobile GSM telephone connected to the network of an operator of mobiles for an intended recipient of short messages (other GSM mobile subscribers or a pager) not belonging to the same mobile telephone network as the call party, nor necessarily to networks linked by roaming agreements or by interconnection agreements for the transmission of short messages (SMS).
the short message (SMS) being composed of a routing envelope with a first field (E1) containing the number of the calling party""s mobile, a second field (E2) intended to receive the number of the first short message transmission centre (SMSC) of the network of the operator of the calling party""s mobile, a third field (E3) containing the called mobile number, as well as a field reserved for the text of the message (TM),
this system comprising short message transmission centres (SMSC) belonging to the same network or to a different network.
This is currently possible from a mobile (GSM or other) capable of comprising text messages (known as xe2x80x9cshort messagesxe2x80x9d) and sending them to other mobiles (GSM, xe2x80x9cpagersxe2x80x9d, etc.). And also from an INTERNET access.
The number of mobile or Internet access (IAP or ISP) network operators makes this ideal of interworking difficult, bearing in mind the technical constraints and the commercial restrictions due to competition.
Interest in such a service is increased if the users can send a message without themselves having to know all the agreements made by their GSM or Internet suppliers for sending messages to other networks.
Such a system which is known will first of all be described below with the aid of FIG. 1 which shows in a general manner the means which currently permit transmission of a short message and the structure of the actual short message.
In a second part, this prior art will be described in a more detailed manner with the terminology used in this field. Since this terminology is used solely and universally in its Anglo-Saxon form it has been necessary to use this terminology in the detailed description, and a glossary has been given at the end of the description in order to explain the different acronyms and abbreviations used in accordance with international GSM standards.
According to FIG. 1, a mobile telephone network (a mobile telephone is more simply called a xe2x80x9cmobilexe2x80x9d) is composed of a base terminal station BTS with which the mobile M1 communicates. This terminal BTS as well as other terminals BTS are connected to a base station concentrator BSC. Several such concentrators BSC of one and the same network operator are connected to a mobile switching centre MSC.
When this centre MSC receives the request for connection of the mobile M1 to a called mobile M2 belonging to the same network, it can establish the communication to this mobile M2 via the same concentrator BSC or another base to the terminal BTS to which the mobile M2 belongs.
In the case of a mobile M3 which does not belong to the network, it is necessary for the centre MSC to use an international gateway with the other network in order to communicate.
The networks are represented in a simplified manner in FIG. 1.
The terminals BTS are distributed territorially in order to be connected to the mobiles of a certain geographical area. All these BTSs are connected to a concentrator BSC. There are several such concentrators BSC. These concentrators are themselves connected to a switching centre MSC.
When a request for a call for telephone communication is made by the mobile M1 to the destination of the mobile M2, the mobile M1 indicates solely the number of the mobile M2 to be reached. This request terminates at one of the centres MSC which in order to known the called M2 from its number must interrogate a database HLC which interprets the number of the called M2 and indicates, if it knows it, the centre MSC which must establish a connection passing via a concentrator BSC, then a terminal BTS.
The database IILR is the database of the subscriber""s network containing its location (even on another network) and its profile.
When the connection is established, voice communication can be made between the mobiles M1 and M2.
In order to pass to another network, if M1 wishes to communicate with a mobile M3 belonging to another operator network, the centre MSC reaches the called M3 by passing via a gateway GMSC to the international telephone network.
The possibility of general voice communication of mobile telephones does not exist for transmission of short messages SMS (short message service) consisting of sending alphanumeric messages to a called party. This called party may be another mobile, of which the screen permits the message to be displayed in alphanumeric text. It may also be a pager, that is to say a portable terminal like a mobile but which can only receive written messages.
Currently for the short message service the network includes one or more short message service centres SMSC linked to a centre MSC. Since the short message service is not provided to all subscribers, this possibility of short messages which exists intrinsically on a mobile can only be used if the subscription provides for it.
The request for transmission and the effective transmission of short messages very generally make use of the network of the mobile telephone operator possibly with certain restrictions.
Thus in order to send a short message SMS, the calling mobile M1 sends its message SMS-MO which arrives at a centre MSC. This latter transmits it to the short message centre SMSC which examines the possibility or barring of transmission of the message. If the short message transmission service does not form part of the possibilities allowed on the mobile M1, the operation is blocked at this level. But if M1 is authorised to transmit short messages to other subscribers to the operator""s network the centre SMSC gives this authorisation and the message is then routed towards the called party M2. The connection is established with a voice telephone communication. The centre SMSC is obliged to interrogate the database HLR via the centre MSC in order to know the path to the called M2.
If the network operator has an agreement with another network in the same country, and if the calling party M1 is authorised to benefit from this service, this possibility is confirmed by the centre SMSC; the centre MSC goes back to the database HLR of M2 in order to know the path to define to the addressee of the message belonging to another network which has a transmission agreement with the present network.
In a general way, the mobile telephone networks are national networks managed by a national operator. For international exchanges the operators have agreements with foreign operators who transmit the calls from a mobile in one country to a mobile abroad.
There are also possibilities for use of the mobile telephone for telephone communication from a foreign country, that is to say from a different network from the national network to which the mobile M1 subscribes. In this case, by virtue of usage (roaming) agreements the mobile M1 which is in a foreign country can access the local network and use the different terminals BTS, concentrators BSC and centres MSC of the country concerned in order to reach a called party in this country or in another country.
However, for different reasons such possibilities do not exist for the transmission of short messages or are not widespread for short messages or at least these possibilities are very limited.
There are also short message services which are strictly limited to a group of subscribers.
It should also be noted that the break in the path of a short message is situated at the level of the centre SSC. Between the mobile M1 and the centre SMSC the short message is entitled SMS-MO (short message sent from a xe2x80x9cmobilexe2x80x9d) whilst downstream of the centre SMSC the message is entitled SMS-MT (a short message sent to a mobile from a service centre).
The transmission of the short messages SMS is explained with the aid of the extremely simplified diagram shown in FIG. 1.
When a calling party (subscriber to a mobile telephone network) wishes to send a short message with the aid of his mobile M1 (mobile functioning as sender of short messages) he keys in his alphanumeric message and the number of the addresses. This message SMS is sent currently to a short message centre SMSC belonging to the network of the operator to which the mobile M1 subscribes.
The number of the SMSC is set automatically in the mobile M1 without the user of the calling mobile having to intervene.
The centre SMSC accepts the transmission of this short message SMS if the called party (receiving mobile or called pager) belongs to the transmission network of the operator to which the mobile M1 subscribes. The transmission is then made by a transmission path which is not explained.
If the message SMS from the mobile M1 is intended for a called party belonging to the network of a different operator but one having an interworking agreement for short messages with the network of the operator of the mobile M1, the centre SMSC transmits the short message to the called party M3 via a SMS-MT by interrogating the HLR of the network of M3.
In order to permit their transmission, the short messages contain in their header a certain number of items of data concerning the routing and the addressee.
In a more precise manner the diagram of FIG. 2 shows the structure of a short message SMS. This message is composed of a routing envelope which constitutes the header of the message and a part reserved for the text of the message (alphanumeric symbols).
The routing envelope ER is composed of a first field E1 containing the number of the calling mobile (M1) (FIG. 2). A second field E2 of the routing envelope ER is reserved for the number of the short message SMS centre. The third field E3 of the envelope ER contains the number of the called party. Finally, the field TM is intended to receive the alphanumeric text of the short message. This field has a length of 160 characters.
Currently according to the prior art the field E1 contains the number of the calling mobile. This number is necessary for the management of the message (accounting) but also for the routing of the message and so that the intended recipient of the message knows the caller.
The second field E2 currently contains the number of the short message centre SMSC of the network to which the mobile M1 subscribes. The transmission of the message is carried out automatically without the message itself containing data concerning the management of this transmission, that is to say the succession of different centres of the operator""s network through which the short message MSM transits.
Finally, the third field E3 contains the number of the mobile called.
A detailed description will be given below of the different known processes for transmission of sent messages and restrictions which mar such transmissions.
IIxe2x80x94Reminder of the different current processes for restricting transmission of short messages from a GSM mobile to the mobile of another operator (case where there are roaming agreements)
The chain of transmission of a short message to its intended recipient is described below with the aid of FIG. 3, which shows two processes for restricting transmission of short messages:
A. The operator (HPLMN) where a mobile subscribes bars it from SMS-MO operation (prepay subscription for example).
Process for restriction at the level of the subscription
The VLR of the VPLMNc (visited network) contains a copy of its subscriber profile where the SMS-MO function is barred. In this case the network will return an error message to the subscriber. Naturally, the VPLMNc can be identical to the HPLMN if the mobile is not roaming. This process is very often implemented (for example for xe2x80x9cprepayxe2x80x9d subscriptions).
B. The Service Centre (RPLMN) refuses the SMS-MO.
The SMSC is operated by a third party (RPLMN) or by the subscription operator (HPLMN) without this changing anything apart from the administration of this refusal. The reason for this refusal may be not to load its SMSC for third party traffic. The fowardShortMessage contains the following address data of the MAP protocol (Messaging Application Protocol) contained in MAP-FORWARD-SHORT-MESSAGE
address of the destination Service Centre
the MSISDN (subscriber""s number) of the calling mobile
the MSISDN (subscriber""s number) of the called mobile (in the field UI)
Process for restriction at the level of the called SMSC
The Service Centre may therefore refuse the deposit of a message:
for subscribers to all the calling networks (except its own)
for all except the subscribers of certain calling networks (a list of numbers must be created) (black list)
for none but the subscribers of certain networks (red list) (a list of numbers in E164 format (ITU standard as previously) must be created)
The called SMSC may be that of the subscription operator (home PLMN) or of a third-party operator (relay PLMN) which has an obligatory roaming agreement permitting an exchange of MAP messages between the networks.
This restriction process is more usual and easily implemented at the level of the SMSCs of the market which are configurable.
C. An international gateway (IGP) between the networks refuses the SMS-MO.
This may be the international gateway at the VLPMN, (transmitting) network end or at the RPLMN (receiving) network end, which will be systematically the case if there is no roaming agreement.
The restriction at the HPLMNd end (RPLMN=HPLMNd) may be implemented by analysis of the Calling Party Address of the SCCP messages.
IIxe2x80x942xe2x80x942nd stage: sending a SMS-MT from the Service Centre
It should be noted that the restriction processes below must however permit an SMSC to send SMS-MTs to its own subscribers even when they are roaming on another network.
It must also be possible:
to bar the other networks possibly from sending SMS-MTs to its own subscribers
to allow the other networks to send MSM-MTs to their subscribers when they are roaming with the operator which has implemented the above restriction.
Example: the roamed SMSCs can send SMS-MTs to subscribers roaming on Chungwha Telecom (Taiwan) but not the Chungwha Telecom subscribers.
The MAP message Send Routing Info for Short Msg sent to the HLR contains:
the MSISDN (subscriber""s number) of the called mobile
the address of the originating Service Centre (RPLMN)
It does not contain the MSISDNs (subscriber number) of the calling mobile (if the SMS-MT follows a SMS-MO).
The HLR will return the subscriber""s IMSI if it finds it, which will then be used for addressing the transmission of the short message.
IIxe2x80x942.1xe2x80x94Description of the mechanism for transmission of MAP messages from the RPLMN to the HPLMN
The SMSC sends a MAP message xe2x80x9cencapsulatedxe2x80x9d in a SCCP message.
Addressing of the SCCP message by the SMSC.
It is sent in a SCCP message containing:
xe2x80x9cCalled Party Addressxe2x80x9d in Q713 format
xe2x80x9cCalling Party Addressxe2x80x9d in Q713 format, the address of the calling SMSC
Case 1
If the calling SMSC does not know (this necessitates creating a database with the addresses of the HLRs (address E164 or E214) all the HPLMN operators with which the RPLMN has roaming agreements it puts:
Calling Party Address=MSISDN of the subscriber who is the intended recipient of the SMS-MT for the xe2x80x9cGlobal Titlexe2x80x9d field of this address.
Case 2
On the other hand if the calling SMSC has the numbering plan of the HPLMN it is capable of deducing (searching a table) from the MSISDN of the called subscriber the Global Title E164 or E214 of the HLR of this subscriber (there is roughly 1 IILR for 100 to 200,000 subscribers). In this case it puts in:
Called Party Address=address of the called HLR
It will be seen below that in this case for the (receiving) HPLMN this removes the possibility of restriction at the level of the receiving IGP.
Addressing of the MTP message to the transmitting IGP (of the RPLMN)
The SCCP message containing the MAP message must be sent by the SMSC to the transmitting IGP. For this the SMSC carries out an xe2x80x9caddress translationxe2x80x9d (into xe2x80x9cSemaphore Pointxe2x80x9d) which will permit the RPLMN to carry out the routing of the message to the transmitting IGP, known this time, by a xe2x80x9cSemaphore Pointxe2x80x9d address (ITU Q713 Standard).
The international network SS7 then transmits the message to the receiving IGP based on the xe2x80x9cCalled Party Addressxe2x80x9d of the SCCP message.
Routing effected by the receiving IGP (of the HPLMN)
This latter analyses the SCCP message (it does not process the MAP message contained) in order to effect the xe2x80x9caddress translationxe2x80x9d, that is to say to find the address of the xe2x80x9cSemaphore Pointxe2x80x9d HLR to which to send it.
If the xe2x80x9cCalled Party Addressxe2x80x9d contains only the subscriber""s number, this necessitates the IGP having a complete numbering plan of the HPLMN. If this plan is not installed, the message will be refused (passive process of restriction or rather xe2x80x9crestriction by defaultxe2x80x9d).
On the other hand, (Case 2 above) if the SMSC has been capable of providing the address E164 or E214 of the HLR, the IGP will be obligatorily capable of making the address translation and will thus route the message to the IILR (on condition that there is a roaming agreement between RPLMN and HPLMN, if not the IGP rejects the message on the basis of the xe2x80x9cCalling Party Addressxe2x80x9d).
Explanation
In fact, if a subscriber of the HPLMN visits the RPLMN (while roaming) and is located, its VLR address (in E214 deduced from its IMSI in E212) must be transmitted at the time of the first switching on of its terminal at its HLR (so that it can receive calls) via the 2 IGP. The receiving IGP must therefore inevitably be capable of making the translation:
address E214 of the receiving LLRxe2x86x92semaphore point of (receiving) HLR.
Afterwards the networks dialogue with the addresses E164.
The HLR therefore responds to the VLR of the visited network by giving its address E164 (contained in a location updating MAP message).
The updates of locations made by the visited VLRs are made to the subscriber""s HLR henceforth using this address E164.
This implies that the receiving IGP is also capable of making the translation.
Address E164 of the receiving HLRxe2x86x92(receiving) HLR semaphore point.
For reasons of symmetry in roaming, the transmitting IGP is also capable of making the translations of addresses E214 and E164 of its HLRs into semaphore point.
IIxe2x80x942.2 Processes of restriction
In FIG. 4 two processes can be seen for restriction of the reception by the IIPLMN of short messages (SMS-MT).
D. The HLR refuses to return the information requested by the Send Routing Info for Short Msg.
Process of restriction at the level of the HLR (HPLMN) of the called mobile
If the MSISDN belongs to the addressed network, the restrictions can be made exclusively on the address of the originating Service Centre (RPLMN).
The HLR can therefore refuse the interrogation:
for the SMSCs of all the calling networks (except its own)
for all except certain calling networks (black list)
for none except certain calling networks (red list)
Process of restriction
The HLR has available black/red lists permitting it to respond selectively to the requests for location information depending upon the originating SMSC. This functionality is progressively added to the latest versions of the HLR software but is not yet generalised.
E. The called MSC refuses the request to send the SMS-MT
As the MAP-FORWARD-SHORT-MESSAGE message contains the IMSI of the called mobile, it would be possible (with regard to the restrictions which might be made by the HLR) to add:
for no calling subscriber of certain networks (black list)
for no calling subscriber except those of certain networks (red list).
It is not possible for the receiving VLR to implement this restriction because the MSISDN information (subscriber numbers) of the calling mobile does not form part of MAP-SEND-INFO-FOR-MT-SMS.
Note that the MAP-FORWARD-SHORT-MESSAGE may contain an empty (xe2x80x9cunknownxe2x80x9d) xe2x80x9ccalling subscriberxe2x80x9d and thus that this use is not very flexible.
F. An international gateway (IGP) between the networks refuses the SMS-MT
This can be the international gateway at the RPLMN end or more usually of the HPLMNd.
The refusal is made on the passage of a SCCP message encapsulating the MAP message xe2x80x9cSend Routing Info for Short Msgxe2x80x9d coming from the SMSC of a RPLMN. The analysis by the IGP is made solely on the addresses of the SCCP messages, as the IGPs do not have the function of analysing the content (MAP messages or others):
Calling Party Address and Called Party Address do not have a roaming agreement
The SMSC has sent its message (Case 1 above) with the MSISDN of the called subscriber as xe2x80x9cCalled Party Addressxe2x80x9d and the IGP has not implemented a numbering plan, the message is then refused (xe2x80x9crestriction by defaultxe2x80x9d).
IIIxe2x80x943xe2x80x943rd stage: (possible) sending of a status report
Via his mobile the subscriber who sends a SMS-MO can ask to receive a confirmation when the SMS-MT has been correctly received by the called subscriber""s mobile (technically a TP-SRR Status Report request bit is positioned in the message sent).
The process is identical, the roles being reversed with respect to the 2nd stage: the SMSC RPLMN sends a message such as xe2x80x9cmessage sent at 08:06:52. Received at 08:07:20xe2x80x9d to the sender of the SMS by interrogating not the HLRd (of the intended recipient) but the HLRc of the sender.
For this (optional) function the SMSC must also have authorization to send a SMS-MT to the subscribers of the network xe2x80x9cexe2x80x9d.
The aim of the present invention is to develop a system of dynamic routing of short message SMS permitting such messages to be transmitted to called parties belonging to networks which cannot normally reach a calling mobile.
To this end the invention relates to a system of the type defined above which is characterised in that:
A) a numbering plan (PN) containing the numbers of the short message transmission centres (SMSC) and the possible interconnections between the different transmission centres (SMSC) and the switching centres (MSC) of the networks of the called mobiles (M1a, . . . M4a),
B) a numbering plan manager (GPN) which from then umber of the called party defines the relay transmission centre or centres (SMSC) in order to reach the switching centre (MSC) visited by the intended recipient of the short message (SMS).